Currently, the research on resource and admission control is a hot topic of international standardization organizations. The International Telecommunication Union—Telecommunication Standardization Sector (ITU-T), Telecommunications and Internet Converged Services and Protocols for Advanced Networking (TISPAN), and the 3rd Generation Partnership Project (3GPP) have researched it to different extents.
Different organizations call the term “resource and admission control” differently, and the functional architecture and the research scope also differ to some extent, as detailed below:
The concept of resource and admission control is initially put forward in the TISPAN. The relevant function is called “Resource and Admission Control Subsystem (RACS)”. FIG. 1 shows a RACS architecture. The RACS correlates the resource requirement at the service layer (IP Multimedia Subsystem (IMS)) with the resource allocation of the network transmission layer, and is responsible for policy control, resource reservation, admission control, Network Address Translation (NAT), and firewall traversal.
The Service Policy Decision Function (SPDF) southbound interface in the RACS architecture is responsible for NAT traversal control and access control, transport protocol selection policy, bandwidth control, Quality of Service (QoS) marking, consumption measurement and statistic report, and resource state synchronization. The southbound interface mentioned herein is a logical interface between the policy decision unit/device and the bearer and transmission unit/device.
The function related to resource and admission control in the ITU-T is a Resource and Admission Control Function (RACF). FIG. 2 shows a RACF architecture, where the Policy Decision Function Entity (PD-FE) southbound interface is responsible for resource reservation and designation, QoS processing (such as packet marking and policy application), access control, NAT and address mapping, resource consumption information report, and dynamic firewall mode selection.
The function related to resource and admission control in the 3GPP is Policy Control and Charging (PCC). FIG. 3 shows the PCC architecture, where the Policy Control and Charging Rules Function (PCRF) southbound interface is responsible for initiation and maintenance of IP Connectivity Access Network (IP-CAN) session connections, PCC decision request and provision, negotiation of an IP-CAN bearer setup mode, and termination of IP-CAN connections.
According to the initial design, the RACS architecture of the TISPAN is oriented to fixed networks; the PCC architecture of the 3GPP is oriented to mobile networks; and the RACF architecture of the ITU-T is oriented to both fixed and mobile networks.
The initial assumptions of the network architecture for resource control and admission control differ between the standardization organizations such as the ITU-T, TISPAN, and 3GPP, and therefore, the development of the standard technologies is not synchronous or consistent between the organizations. With the emergence and the development of the ALL-IP technology and the Fixed-Mobile Combination (FMC) technology, network operators and equipment manufacturers take the initiative in converging the network architecture under different standards with respect to the components and interfaces that share common features, with a view to unifying the relevant network elements and interfaces gradually, simplifying the network and reducing the cost of network construction.
FIG. 4 and FIG. 5 show most interfaces in the foregoing architectures. Currently, the combination of the southbound interfaces Gx, Re and Ia is proposed in the industry. In FIG. 5, the double arrowhead indicates the interfaces that need to be converged. Besides, for combination of such interfaces, combination of these bearer and transmission devices is also required: Policy and Charging Enforcement Function (RCEF), Core Border Gateway Function (C-BGF), Gateway (GW), Gateway GPRS Support Node (GGSN), IMS Access GW, and Broadband Access Server (BRAS).
In the process of implementing the present invention, the inventor finds at least the following difficulties in achieving such combination:
1. It is difficult for the existing standard systems to compromise with each other to implement the uniform southbound interface.
2. It is technically difficult to implement uniform southbound interfaces and relevant processes even if different standard systems can compromise with each other.
3. The existing network devices should be changed massively to support uniform interfaces after combination, and the high cost makes the combination impracticable.